Method PlayAtTime AVAudioPlayerNode IOS Xamarin不起作用

Question

我想在特定的时间播放声音，我在AVAudioPlayerNode上使用了PlayAtTime方法，这是我的代码：

 private AVAudioUnitReverb reverb;
 private AVAudioEngine engine;
 private AVAudioFile file;
 private AVAudioPlayerNode audioPlayerNode;

 public void PlayBackgroundMusic(byte[] data, string extention, string filename, double playingAt)
    {
        try
        {
            NSError err;
            engine = new AVAudioEngine();
            audioPlayerNode = new AVAudioPlayerNode();
            engine.AttachNode(audioPlayerNode);

            filename = filename.Replace(@"/", @"%2F").Replace(" ", @"%20");
            NSUrl url = new NSUrl(filename);
            file = new AVAudioFile(url, out err);

            reverb = new AVAudioUnitReverb();
            reverb.LoadFactoryPreset(AVAudioUnitReverbPreset.SmallRoom);

            engine.AttachNode(reverb);

            ConnectAudioNodes(audioPlayerNode, /*timePitch,*/ reverb, engine.OutputNode);

            audioPlayerNode.Stop();                

            engine.StartAndReturnError(out err);
            var hostTime = AVAudioTime.HostTimeForSeconds(playingAt);
            audioPlayerNode.ScheduleFile(file, new AVAudioTime(hostTime), null);
            audioPlayerNode.PlayAtTime(new AVAudioTime(hostTime));                   

            backgroundSong = filename;
        }
        catch (Exception ex)
        {
            MetricsManager.TrackEvent($"AudioService.PlayBackgroundMusic error {ex.Message}");
        }
    }

但是代码不起作用。音频总是从头开始。

Answer 1

您的PlayAtTime需要基于您一起延迟和/或同步的音频播放器实例。

从AVAudioPlayer.DeviceCurrentTime获取当前时间，并添加您希望在未来启动播放器的秒数(以双精度为基数)：

示例：

var player1 = AVAudioPlayer.FromUrl(new NSUrl("FireplaceWoodCrackle.mp3", ""), out NSError nsError);
Debug.WriteLine(nsError?.Description);
if (nsError == null)
    player1.PlayAtTime(player1.DeviceCurrentTime + 10); // play at 10 seconds in the future